[BUGFIX] Use proper extractor key for download archive (#840)
For less popular sites, ytdl-sub's custom download archive was not working. This was because we weren't using the right extraction key (though it still worked for YouTube, Bandcamp, Soundcloud, and others). This bugfix should now exactly match yt-dlp's and never be a problem again.
Huge thanks to @Svagtlys for root-causing this 🤝